Titanium trichloride catalyst complex and process for the production thereof

ABSTRACT

A titanium trichloride catalyst complex is produced by reducing titanium tetrachloride with an organo-metal compound and then activating the resulting reduced solids by treatment with a chlorinated hydrocarbon and titanium tetrachloride in the presence of a Lewis base complexing agent. The employment of the chlorinated hydrocarbon and titanium tetrachloride in the presence of the Lewis base complexing agent unexpectedly produces a synergistic effect whereby activating conditions, e.g., temperature, time and TiCl 4  concentration can be employed resulting in a titanium trichloride complex having superior alpha-olefin polymerization properties as compared to titanium trichloride catalyst complexes obtained by treatment under the same conditions in the absence of either titanium tetrachloride or chlorinated hydrocarbon. Moreover, unexpectedly high yields of activated catalyst can be recovered without loss of activity.

This is a division of application Ser. No. 811,507, filed June 30, 1977,now U.S. Pat. No. 4,151,112.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to titanium trichloride catalyticcomplexes useful as a catalyst component for the stereoregularpolymerization of alpha-olefins and more particularly pertains to anovel process for preparing a titanium trichloride catalyst complexhaving excellent alpha-olefin polymerization properties, e.g.,stereospecificity, catalytic efficiency and narrow particle sizedistribution, in high yields.

2. Discussion of the Prior Art

As a method of producing crystalline polyolefin, it has been widelyknown to use a polymerization catalyst system comprising, incombination, a catalyst component consisting of a low valence transitionmetal halide and an organo-metal halide compound. More particularly, ona commercial scale, a titanium trichloride composition hasconventionally been used as the low valence metal halide in combinationwith an aluminum alkyl compound as co-catalyst or activator.

There are many techniques described in the literature for preparing atitanium trichloride composition useful as catalyst in alpha-olefinpolymerization. Generally speaking, several of such techniques includereducing titanium tetrachloride with hydrogen or aluminum powder at hightemperature, followed by crushing the resulting reduced product foractivation. Such catalyst components are widely used commercially, butleave much to be desired. More particularly, the polymerization speedand stereoregularity of such titanium trichloride catalysts require theutilization of a large amount of the expensive catalyst in alpha-olefinpolymerization while a great cost is simultaneously required fortreatment of non-crystalline polymers produced as byproduct. Moreover,the grinding step required in activating such titanium trichloridecompositions results in wide particle size distribution so that polymerobtained by using such catalyst components also has wide particle sizedistribution, resulting in trouble in handling such polymers.

Many efforts have been made to overcome the aforementioneddisadvantages. As a method of modifying the titanium trichloridecomposition, it has been proposed to add metal halides, alkyl aluminumcompounds, halogenated hydrocarbons, ethers, esters, ketones, etc. Morespecifically, several references have described reduction of titaniumtetrachloride with aluminum metal in the presence of certain halogenatedhydrocarbons or treating the reduced product therewith. See, forexample, U.S. Pat. No. 3,365,434.

It has also been proposed to add certain halogenated hydrocarbons toaluminum metal or hydrogen reduced titanium trichloride prior to orduring the grinding-activation step. See U.S. Pat. No. 3,701,763; U.S.Pat. No. 3,560,146; British Pat. No. 1,414,312 and Japanese Pat. No.J7600097, both to Mitsubishi Petrochemical Company Ltd.; U.S. Pat. No.3,875,126; Japanese application No. 64/24272, published Oct. 29, 1964,to Mitsui Chemical. Further, other references have described extractingresulting ground or pulverized aluminum metal reduced titaniumtrichloride compounds with certain halogenated hydrocarbons. See U.S.Pat. No. 3,701,763; U.S. Pat. No. 3,850,899; and British Pat. Nos.1,336,770; 1,359,328; and 1,351,822, to name a few.

These methods, as well as others described in the literature employingother modifiers as mentioned hereinbefore, however, have not overcomethe disadvantages associated with such titanium trichloride catalysts.Such modifications have not sufficiently improved particle sizedistribution, stereospecificity and catalytic activity of suchcatalysts.

Other techniques known in the art for preparing titanium trichloridecatalyst components, generally speaking, include reducing titaniumtetrachloride with an organo-metal compound, particularly anorganoaluminum compound, at low temperature. Such techniques have theadvantage in producing a catalytic component with a relatively evenparticle size; however, the resulting titanium trichloride compositionobtained is normally a brown beta-crystalline type titanium trichloridewith alpha-olefin polymerization properties which are very inferior.However, as known, such brown beta-type titanium trichloridecompositions can be activated by crystal conversion to a more activeviolet, or purple, titanium trichloride normally having predominantalpha, gamma or delta crystalline structures.

More particularly, it is known that the brown beta-type titaniumtrichloride can be converted to more active, i.e., more stereospecific,higher catalytic activity, violet titanium trichloride by heating at notgreater than about 200° C., usually about 150°-160° C. See, for example,U.S. Pat. No. 2,971,925 to Winkler et al, U.S. Pat. No. 3,261,821 toVanderberg, U.S. Pat. No. 3,562,239 to De Jong et al and U.S. Pat. No.3,979,372, to name a few. However, as known, the polymerizationproperties of polymerization speed and stereoregularity of such TiCl₃compounds when used as a polymerization catalyst are not superior to theaforementioned aluminum-reduced pulverized titanium trichloridecompositions.

Another technique for activating beta-type titanium trichloridecompounds prepared by organo-metal reduction of TiCl₄ which hasdeveloped considerable interest in the industry has been described inBritish Pat. Nos. 1,391,067 and 1,391,068 to Solvay et Cie. Thus, inthese patents, there is described a method of preparing a catalystcomponent capable of giving relatively high polymerization speed, highstereoregularity and excellent particle size distribution by reducingtitanium tetrachloride with an aluminum alkyl halide at low temperatureto form a beta-type titanium trichloride composition and then treatingit with a complexing agent and titanium tetrachloride to convert into aviolet delta-type catalyst solid. However, this method has thedisadvantage that, in order to get high polymerization activity, it isnecessary in the activation step to use titanium tetrachloride in highconcentrations of 15% by volume or more, preferably 30-40% by volume, asdescribed in the patents. Moreover, it has been found that when using acomplexing agent other than diisoamyl ether, the activated titaniumtrichloride composition is not substantially improved. Furthermore, whencertain ethers are substituted, e.g., n-butyl ether, severe fracturingof the catalyst solids occurs with the required high concentrations oftitanium tetrachloride. As known, diisoamyl ether and titaniumtetrachloride reagents are expensive, thus the production costs of asatisfactory catalyst component in accordance with this described methodon a commercial scale is high. Moreover, the necessary employment oftitanium tetrachloride in high concentrations in the aftertreatment steppresents safety hazards.

Yet another technique for activating beta-type titanium trichloridecompounds, obtained by organometal reduction of TiCl₄ at lowtemperature, has been proposed which includes treating the beta-typetitanium trichlorides with certain halogenated hydrocarbons. Moreparticularly, in Japanese Pat. Nos. J-50108-383 and J-50108-384 toMitsubishi Petrochemical Company Ltd. (1975), a process is described inwhich TiCl₄ is reduced at low temperature with an aluminum alkyl halideand the resulting brown precipitate is aftertreated with isoamyl etheror alcohol and carbon tetrachloride to give a red-purple solid whichallegedly has excellent alpha-olefin polymerization properties.

Similiarly, Japanese Pat. No. JA-7206409 (1972) to Mitsui PetrochemicalCo. describes a method whereby titanium tetrachloride is reduced with anorganoaluminum halide in the presence of a halomethane, e.g., CCl₄,HCCl₃, etc., or the halomethane added to the reduction slurry, followedby heating.

Additionally, Japanese Pat. No. J 51030593 to Mitsubishi Chemical Ind.K.K. discloses treating an organoaluminum reduced TiCl₄ solid with acomplexforming agent, e.g., an ether, and carbon tetrachloride ortitanium tetrachloride.

In recently published Belgian Pat. No. 842,591 to Shell International(1976), a process is described for converting beta-type TiCl₃ to themore active violet TiCl₃ by heating the beta-TiCl₃ in the presence of anorganic halide, specifically, certain chlorinated hydrocarbons asspecified. As disclosed, the brown TiCl₃ reduced solid is preferablypretreated with a complexing agent, an ether, and washed prior to theorganic halide-heat treatment. The addition of the organic halide isdescribed as causing the conversion of the catalyst at a lowertemperature, resulting in higher catalyst activity.

Such methods using organic halides, however, have the disadvantage that,in order to obtain a titanium trichloride catalyst component havingalpha-olefin polymerization properties, i.e., high stereospecificity andcatalytic efficiency, superior to commercially available TiCl₃ catalystsobtained by aluminum reduction and grinding, referred to above, there isnecessarily a significant sacrifice in catalyst yield. As known, manyorganic halides, e.g., chlorinated hydrocarbons, act as solvents fortitanium trichloride compositions. Hence, in such known processes theremust be some sacrifice in either catalyst yield or overall catalyticperformance achieved.

SUMMARY OF THE INVENTION

The present invention provides a process for the production of atitanium trichloride catalyst complex for use in thestereopolymerization of alpha-olefins which overcomes theabove-mentioned disadvantages associated with known processes. Inaccordance with the present invention, a titanium trichloride reducedsolids, obtained by the reduction of titanium tetrachloride with anorgano-metal compound at low temperature, is treated with a chlorinatedhydrocarbon and titanium tetrachloride in the presence of a complexingagent. The chlorinated hydrocarbon and titanium tetrachloride in thepresence of the complexing agent unexpectedly exert a synergistic effectwhereby a crystal conversion of the titanium trichloride reduced solidsis obtained without sacrifice in catalyst yield. Additionally, thesynergistic activating treatment of the present invention permits theproduction of a titanium trichloride catalyst complex under mildactivation conditions, such as temperature, time and titaniumtetrachloride concentration, which resulting titanium trichloridecatalyst complex has alpha-olefin polymerization properties superior toa titanium trichloride catalyst complex obtained under the sameconditions in the absence of either the titanium tetrachloride or thechlorinated hydrocarbon.

Thus, the present provides a novel process for producing a titaniumtrichloride catalyst complex that can exhibit very excellent propertiesor performances when used as a catalyst for the polymerization ofalpha-olefins in high yields, thereby significantly reducing catalystand polymer manufacturing costs, as well as reducing safety hazardsassociated with utilizing titanium tetrachloride in high concentrations.Moreover, the novel process enables the utilization of many types ofchlorinated hydrocarbons which heretofore have been found to be unableto activate the beta catalysts by conversion or to result in extremelylow yields of activated catalyst.

DETAILED DESCRIPTION OF THE INVENTION

The titanium trichloride-containing reduced solid obtained by reducingtitanium tetrachloride with an organo-metal compound according to thepresent invention (which will hereinafter be referred to as "reducedsolid") is a reduced solid whose color is usually brown to red-violetand which contains metal compounds, for example, aluminum compounds,which has a complicated composition. In these reduced solids, thetitanium trichloride component is usually of the beta-type crystallinestructure. As the organo-metal compound, there are generally used,individually or in combination, organoaluminum compounds,organomagnesium compounds and organozinc compounds (which willhereinafter be referred to as "organo-metal compounds"). Preferably, thereduction is carried out by the use of organoaluminum compounds. Thereduced solid obtained in this way contains a metal compound or amixture or complex compound thereof, in particular, an aluminum compoundor a mixture or a complex compound thereof in uniform state, whichpossibly interact with complexing agent, chlorinated hydrocarbon andtitanium tetrachloride to some extent, thus improving the catalyticproperties of the composition in conventional alpha-olefinpolymerization.

The process of the invention is deemed to be capable of increasing thealpha-olefin polymerization properties and improving titaniumtrichloride component catalyst yields through employment of any reducedsolid described above by any process known in the art. That is to say,the reduction step of titanium tetrachloride with an organo-metalcompound is not critical in the present invention and, accordingly, anytechnique heretofore described in the art or hereafter discovered may beemployed to obtain the reduced solids.

In any event, it is preferred in the reduction step to use anorganoaluminum compound represented by the general formula R_(n)AlX_(3-n), wherein R represents an alkyl group or aryl group, Xrepresents a halogen atom and n represents a suitable numeral within therange of 1≦n≦3, or a mixture or a complex compound thereof. Usually,alkyl aluminum compounds having 1 to 18 carbon atoms, preferably 2 to 6carbon atoms, are used, such as trialkyl aluminums, dialkyl aluminumhalides, monoalkyl aluminum dihalides, and alkyl aluminum sesquihalides,mixtures or complex compounds thereof. Examples of the trialkyl aluminumare trimethyl aluminum, triethyl aluminum and tributyl aluminum.Examples of dialkyl aluminum halide are dimethyl aluminum chloride,diethyl aluminum chloride, dibutyl aluminum chloride, diethyl aluminumbromide and diethyl aluminum iodide. Examples of the monoalkyl aluminumdihalide are methyl aluminum dichloride, ethyl aluminum dichloride,butyl aluminum dichloride, ethyl aluminum dibromide and ethyl aluminumdiiodide. Moreover, ethyl aluminum sesquichloride is given as an exampleof the alkyl aluminum sesquichloride. Triethyl aluminum, diethylaluminum chloride, ethyl aluminum dichloride, ethyl aluminumsesquichloride or their mixtures or complex compounds, for example, amixture of diethyl aluminum chloride and ethyl aluminum dichloride isparticularly preferable because these compounds are readily obtainablecommercially and exhibit excellent effects.

The reduction of titanium tetrachloride is ordinarily carried out byadding the above-described organo-metal compound or its solutiondropwise to a solution of titanium tetrachloride dissolved in an inertdiluent such as an aliphatic hydrocarbon having 5 to 12 carbon atoms ata temperature of from about -50° C. to about +30° C. for a period oftime of about 30 minutes to about 3 hours, although the reverse additionmethod can be employed.

The quantity of organo-metal compound used is ordinarily 0.75 to 5 gramatoms as metal per 1 gram atom of titanium. When titanium tetrachlorideis reduced with diethyl aluminum chloride (DEAC) or a mixture of DEACand ethyl aluminum dichloride (EADC), these reagents are preferablymixed in a molar ratio of TiCL₄ :DEAC=1:0.75 to 1:2 and TiCl₄:DEAC:EADC=1:0.5:0.5 to 1:1:1.

Preferably, the temperature of the reduction is maintained relativelyconstant until all reagents have been added. The mixture is then usuallyaged at an elevated temperature of from about 0° to about 100° C. forabout 1 to 3 hours, but this treatment is not always necessary. Theresulting reduced solid, which usually contains titanium trichloride inthe brown beta crystalline structure, depending upon specificorganometal compounds, reagent ratios, reaction conditions, etc., used,is then separated by a suitable method, optionally washed with an inertdiluent and optionally dried.

In accordance with the invention, the reduced solids product thusobtained is then subjected to an activation step by contact with a Lewisbase complexing agent, a chlorinated hydrocarbon, and a minor amount oftitanium tetrachloride, preferably at an elevated temperature until acrystal conversion of the titanium trichloride component is obtained.Usually, the titanium trichloride component is converted to the purpleor violet form normally indicative of an alpha, gamma or deltacrystalline-type titanium trichloride.

This contacting can be effected in numerous ways, such as by adding theabove described reduced solids, optionally in an inert diluent, such asaliphatic hydrocarbon, to a mixture of complexing agent, chlorinatedhydrocarbon and titanium tetrachloride, reverse addition thereof, anysequential addition of these activation compounds to the reduced solidsand so forth. Additionally, the reduced solids can be pretreated withthe complexing agent, preferably at a temperature of about ambient toabout 80° C. to obtain a complexed reduced solids component as describedin several prior art references, e.g., British Pat. No. 1,391,067;Belgian Pat. No. 842,591; and Japanese Pat. No. J-50108-383 referred tohereinabove. This resulting complexed reduced solids can then becontacted with the chlorinated hydrocarbon and titanium tetrachloridefor the above-mentioned crystal conversion of the reduced solidsproduct.

However, it it preferred to carry out the activation step whereby thecomplexing agent, chlorinated hydrocarbon and titanium tetrachloride areadded to the reduced solids, or vice versa, with no washing orseparation step between any reactant addition. Such technique is moresimple and produces optimum catalyst activation and yield.

The activation conditions employed may vary widely, depending upon thespecific chlorinated hydrocarbon, complexing agent and concentration oftitanium tetrachloride employed. Most unexpectedly, however, theutilization of the chlorinated hydrocarbon in combination with titaniumtetrachloride in the presence of the complexing agent results in acrystal conversion of the titanium trichloride reduced solids product atconditions, e.g., an elevated temperature, and treatment time, muchlower and shorter than is required to obtain such crystal conversion bytreatment of the same reduced solids in the absence of either thechlorinated hydrocarbon or the titanium tetrachloride where the titaniumtetrachloride is similarly used at the same low concentration. Moreover,as illustrated more particularly in the following Examples, theemployment of the synergistic activation mixture of the presentinvention results in the production of a titanium trichloride catalystcomplex having significantly superior alpha-olefin polymerizationproperties, as evidenced by stereospecificity and/or catalystefficiencies, as compared to a titanium trichloride catalyst complexproduced under the same activation conditions in the absence of one ofeither the titanium tetrachloride or the chlorinated hydrocarbon.

Another significant aspect of the present invention is that, through theutilization of milder activation conditions, catalyst yield can besignificantly increased without a concomitant decrease in catalyticactivity, e.g., alpha-olefin polymerization properties. In fact, asillustrated in the following Examples, catalyst yield is notsignificantly affected even when more severe temperature conditions areemployed which heretofore were found necessary to obtain high catalyticactivity.

The complexing agent used in the present invention may be any compoundheretofore employed for complexing titanium trichloride catalyticcompounds. See, for example, British Pat. No. 3,391,067. As known, suchcomplexing agents are compounds containing one or more electron donatingatoms or groups, preferably Lewis bases. Such Lewis base complexingagents include ethers, thioethers, thiols, organophosphorus compounds,organonitrogen compounds, ketones, esters and the like.

Useful examples of the ether are diethyl ether, diisopropyl ether,di-n-butyl ether, diisobutyl ether, propylphenyl ether, diisoamyl ether,di-n-hexyl ether, di-2-ethylhexyl ether, di-2-ethylheptyl ether, allylethyl ether, allyl butyl ether, diphenyl ether, anisole, phenetole,chloroanisole, p-methylanisole, bromoanisole, dimethoxybenzene, etc.Useful examples of the thioether are diethyl thioether, di-n-propylthioether, dicyclohexyl thioether, diphenyl thioether, ditolylthioether, ethyl phenyl thioether, propyl phenyl thioether, diallylthioether, etc. Useful examples of the organo phosphorus compound aretri-n-butylphosphine, triphenylphosphine, triethyl phosphite, tributylphosphite, etc. Useful examples of the organo nitrogen compound arediethylamine, triethylamine, n-propylamine, di-n-propylamine,tri-n-propylamine, aniline, dimethylaniline, etc. In particular, ethersare preferably used and, above all, those having 4 to 16 carbon atomsare more desirable. From the standpoint of economy, n-butyl ether is themost preferred.

As the chlorinated hydrocarbon, there can be used chlorinated saturatedor unsaturated aliphatic hydrocarbons or chlorinated aromatichydrocarbons or their isomers, preferably containing 1 to 20 carbonatoms.

Examples of useful saturated aliphatic chlorinated hydrocarbons includethe chlorinated methanes, such as carbon tetrachloride, chloroform,dichloromethane, chlorinated ethanes, such as hexachloroethane,pentachloroethane, tetrachloroethane, etc., chlorinated propanes,butanes, and so forth. Useful unsaturated chlorinated hydrocarbonsinclude, for example, tetrachloroethylene, allyl chloride,1,3-dichloropropane, 1,3-dichlorobutene-2, 1,4-dichlorobutene-2,hexachloro-n-butene-2, hexachlorocyclopentadiene, etc. Further, by wayof example, useful halogenated aromatic hydrocarbons include thechlorinated benzenes, e.g., hexachlorobenzene, benzyl chloride, benzyltrichloride, as well as those having a chlorinated side chain.

It is to be understood that the above listing of example compounds isnot intended to be complete. Any chlorinated hydrocarbon can be used inthe present invention. Those chlorinated hydrocarbons having 1 to 8carbon atoms and 2 to 6 chlorine atoms have been found to have largereffects and, accordingly, are more preferred.

It is particularly preferred to utilize C₂ chlorinated hydrocarbonswhich, for example, include hexachloroethane, pentachloroethane,tetrachloroethane, trichloroethane, dichloroethane, tetrachloroethylene,trichloroethylene, dichloroethylene and the like. The beneficial effectof such C₂ chlorinated hydrocarbon increases with saturation and theincrease of the number of chlorine atoms per molecule. Hence,hexachloroethane is most preferred above all inasmuch as optimum resultshave been obtained therewith in regard to alpha-olefin polymerizationproperties of stereospecificity, catalytic efficiency, polymer particlesize distribution as well as catalyst yield.

A most important aspect of the present invention is the discovery thatthe synergistic activation system of the invention significantlyimproves TiCl₃ crystal conversion and catalyst yield when chlorinatedhydrocarbons with relatively stable chloride-carbon bonds, e.g.,vinyllic chloride bonds, chloromethanes, etc., are employed as anactivating agent. Heretofore, the utilization of such chlorinatedhydrocarbons with relatively stable-chloride bonds, when utilized aloneor in the presence of a complexing agent, would not produce significantcrystal conversion of a beta-type titanium trichloride component exceptunder relatively severe activation conditions which resulted inrelatively low activated catalyst yields, e.g., below about 50%,theoretical. Unexpectedly, these relatively stable chlorohydrocarbons inthe presence of a minor amount of TiCl₄ and complexing agent readilyconvert brown titanium trichloride compounds to the more active purpleform under comparatively mild temperature conditions and catalyst yieldis significantly increased. Thus, the present invention permits theutilization of a wide variety of chlorinated hydrocarbons as mentionedabove in the production of titanium trichloride catalyst components inhigh yields.

Another significant aspect of the present invention is the discoverythat only a minor amount of titanium tetrachloride is required to obtainthe synergism of the activation step. Thus, the present invention doesnot suffer from the disadvantages associated with prior art techniquesnecessarily utilizing high concentrations of titanium tetrachloride inorder to obtain a catalyst with superior olefin polymerizationproperties.

For the above-described activation treatment, there are optimumconditions depending upon the property, composition and the like of thereduced solid, titanium tetrachloride concentration, and particularLewis base complexing agent and chlorinated hydrocarbon employed, etc.Generally, the treatment is carried out at an elevated temperature ofabout 50° C. to about 150° C. for about 5 minutes to about 20 hours,preferably 30 minutes to about 5 hours at about 60° to about 80° C. At alow temperature, this treatment should be carried out for a long timeand at a high temperature, it should be carried out for a relativelyshort time. The quantities of chlorinated hydrocarbon, complexing agentand titanium tetrachloride are not particularly limited; however, asnoted hereinabove, only a minor amount of titanium tetrachloride isrequired. This usually ranges in an amount of about 0.1 to about 2.0mols titanium tetrachloride per one mol titanium trichloride in thereduced solids. A preferred range is about 0.5 to about 1.25 mols TiCl₄per mol titanium trichloride per reduced solids titanium trichloride.The titanium tetrachloride is usually present in the activation step ina concentration of about 2 to about 15 volume percent, based upon thetotal volume. Preferred titanium trichloride concentration is about 5 toabout 10 volume percent. Such titanium tetrachloride concentration canbe obtained by utilization of an inert diluent, if necessary.

The Lewis base complexing agent is usually employed within the range ofabout 0.1 to about 2.0, preferably 0.5 to about 1.0, mols per one mol ofreduced solids titanium trichloride. The chlorinated hydrocarbon isusually employed in an amount of 0.1 to about 10, preferably about 0.7to about 2 mols per one mol titanium trichloride of the reduced solids.

In a preferred embodiment where hexachloroethane is utilized as thechlorinated hydrocarbon, it is particularly preferred to carry out theactivation step at an elevated temperature within the range of about 60°to about 85° C. for about 30 minutes to about 3 hours. As illustrated inthe following Examples, the resulting titanium trichloride catalyticcomplex has excellent stereospecificity, catalytic efficiency andparticle size distribution when used in a conventional process foralpha-olefin polymerization. Additionally, the activated titaniumtrichloride catalyst complex thus produced can be recovered in excellentcatalyst yield, approaching or equal to 100% theoretical.

The titanium trichloride catalyst complex resulting from theabove-described activation step of the present invention can berecovered by separation from the chlorinated hydrocarbon, complexingagent, titanium tetrachloride and inert solvent by any known techniqueand can be optionally washed with an inert solvent. The recoveredcatalyst can then be contacted with an organoaluminum compound as aco-catalyst in a conventional manner as it is or after drying, thusobtaining a catalyst for the polymerization of alpha-olefins.

The titanium trichloride catalyst of the present invention is ordinarilyused as a catalyst for the polymerization of alpha-olefins in contactwith an organo-metal compound which is used as a co-catalyst for theZiegler-type catalyst, for example, monoalkyl aluminum dichloride, inconjunction with Lewis bases, dialkyl aluminum monochloride or trialkylaluminum can be used. If desirable, various compounds, for example,complexing agents such as used in the present invention, can further beadded as a third component. The titanium trichloride catalyst componentof the present invention is very excellent as a catalyst for thehomopolymerization or copolymerization of alpha-olefins such aspropylene, butene-1,4-methylpentene-1, etc., and can give uniformpolymer grains with a high polymerization activity and highstereoregular polymer ratio in the polymerization of such alpha-olefinsin a gaseous phase, liquid monomer or inert solvent. Moreover, aspreviously pointed out, the inventive process results in such titaniumtrichloride catalyst in high yield, thus reducing overall catalyst andalpha-olefin polymerization costs.

In order to illustrate the present invention, the following Examples aregiven. In each Example, the formation of catalyst was carried out byreduction and crystal conversion in the following equipment andfollowing procedure, unless otherwise specified.

A 500 ml round-bottom flask, without baffles, equipped with aflat-bladed mechanical stirrer, a thermometer and an addition port iscooled to -5° C. in a Dry Ice/isooctane bath. The stirrer had two bladesmounted at 180°, with an overall diameter of 6 cm. The entire assemblyand all catalyst preparations are maintained in an inert atmosphere. Tothe cooled flask, TiCl₄ (1.5-3.0 molar in n-heptane) is added and thesolution is stirred at a rate between 210 and 400 rpm. The stirring rateis maintained as closely as possible to a specific value during thepreparation, i.e., 250±10 rpm. To the TiCl₄ solution, diethylaluminumchloride or other reducing agent (1.0 to 3.5 molar in n-heptane) isadded over a period of three hours. When all the diethylaluminumchloride solution has been added (1 mol of TiCl₄ /mol of diethylaluminumchloride [DEAC]), the mixture is warmed to +65° C. at a rate of 1.0° C.per minute. The stirred reaction mixture is maintained at thistemperature for one hour. The reaction mixture is then cooled and thecatalyst is filtered and washed twice with boiling heptane. This solidcatalyst is dried and weighed and is referred to as the brown,beta-crystalline reduced solid.

To a 250 cc thick-walled bottle are added a magnet, hydrocarbon solvent,e.g., hexane or heptane, and 5.0 g of reduced solid. To the slurry areadded the chlorohydrocarbon (neat or in hydrocarbon solution), TiCl₄,and the complexing agent. The reaction mixture is heated to thespecified temperature, held at that temperature for a specified lengthof time, and the final reaction mixture is cooled, filtered and washedfive times with 50 cc fractions of boiling heptane. The final catalystis dried under reduced pressure, weighed and used in the followingpolymerization tests.

The catalysts were tested for polymerization by conventional techniques(reaction conditions 65°±0.1° C.; 765±5 mm total pressure [C₃ ⁼ and C₇diluent]; 2 hours reaction time; 2AlEt₂ Cl:1TiCl₃ mol ratio; 5-7 mmolsof TiCl₃ catalyst per 500 cc of heptane polymerization diluent).Catalytic efficiency was determined by dividing the total amount ofpolymer produced by the amount of catalyst that was used, e.g., gms ofdry polymer recovered plus gms of solvent soluble polymer divided by gmsof catalyst. Catalyst stereospecificity was determined by hot-heptaneinsoluble content of resulting polypropylene powder, after propylene andcatalyst removal in a conventional manner by extraction with boilingheptane for 1.5 hours using a Soxhlet extractor (referred to hereafteras C₇ Insol., %).

EXAMPLE 1

A brown, beta-crystalline reduced solid (5.0 gms) prepared according tothe general procedure described above (TiCl₄ :DEAC mol ratio=1) wasadded to a 250 ml glass bottle containing a magnet and 33.3 ml of a 0.75molar solution of hexachloroethane in purified heptane. To this slurry,titanium tetrachloride (2.75 ml) and n-butyl ether (2.53 ml) were added,and the mixture was heated at 65° C. for 2 hours. The mol ratio of theactivation system was 0.6 n-butyl ether:1C₂ Cl₆ :1TiCl₄ per 1 mol TiCl₃of the reduced solid. The TiCl₄ concentration was less than 8 volumepercent. After the heating at 2 hours, a resulting purple solid wasfiltered, washed five times with 50 cc portions of boiling heptane anddried. 3.71 g of catalyst was recovered, which equals to about 100% ofthe theoretical yield. The catalyst had a composition of 0.09 Al:Ti molratio and 92.8 wt. % of the catalyst was comprised of Al,Ti,Cl. Thecatalyst was then tested in the above-described polymerization systemwith the following results: catalyst efficiency, w/w,=141; C₇ Insol.%=98.4.

COMPARATIVE EXAMPLES 1-6

Several samples (5.0 g) of brown beta-crystalline reduced solid preparedaccording to the above-described procedure (TiCl₄ :DEAC mol ratio=1)were separately treated with either n-butyl ether, hexachloroethane,tetrachloroethylene, or TiCl₄ at treatment conditions set forth in TableI. The resulting catalysts, along with a commercially available titaniumtrichloride catalyst, TiCl₃ AA (TiCl₃ 1.1, an aluminum metal reduced,ballmilled TiCl₃ catalyst sold by Stauffer Chemical Company), were thentested by the above-described polymerization system. The results of thepolymerization test are set forth in Table I. A comparison of these dataillustrates that the activating agents employed by themselves do notresult in a TiCl₃ catalyst component having catalyst efficiencies andstereospecifities superior to the commercially available titaniumtrichloride catalyst.

                                      TABLE I                                     __________________________________________________________________________                               Catalyst Properties                                       Activation                    Composition                              Comparative                                                                          System.sup.(a)                                                                         Treatment  Cat. Eff.,                                                                         C.sub.7 Insol.                                                                     Mol Ratio                                                                           Wt. %                              Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub.4                                                                        ° C.                                                                      Hrs                                                                              Yield %                                                                            W/W  %    Al:Ti Al,Ti,Cl.sup.(b)                   __________________________________________________________________________    1      0 0  0   -- -- 100  12   86.5 0.5   --                                 2      1 0  0   35 1  100  97   78   0.1   --                                 3      0 0  1   65 2  100  <40  92   0.3   90                                 4      0 1.sup.(c)                                                                        0   65 2   60  9    78   1.2   88                                 5        .sup.(d)                                                                             -- -- --   42   93   0.33  100                                6      0 1.sup.(e)                                                                            80 3   58  3    73   --    --                                 __________________________________________________________________________     .sup.(a) Mol ratios of BU.sub.2 O:chlorinated hydrocarbon:TiCl.sub.4 per      mol TiCl.sub.3 in reduced solids.                                             .sup.(b) Weight percent, as determined by xray fluorescence.                  .sup.(c) C.sub.2 Cl.sub.6                                                     .sup.(d) TiCl.sub.3 AA (TiCl.sub.3 1.1 sold by Stauffer Chemical Company)     .sup.(e) C.sub.2 Cl.sub.4                                                

COMPARATIVE EXAMPLES 7-11

Several samples (5.0 g) of brown, beta-crystalline reduced solidprepared according to the general procedure described above (TiCl₄ :DEACmol ratio=1) were treated with combinations of n-butyl ether and TiCl₄(Comparative Example 7), or sequentially with n-butyl ether and TiCl₄according to activation conditions described in Example 1 of BritishPat. No. 1,391,067 to Solvay & Cie. (Comparative Example 8) andcombinations of hexachloroethane and titanium tetrachloride (ComparativeExamples 9-11). Details of each experiment and results are set forth inthe following Table II, along with such details of Example 1, set forthfor comparative purposes. Polymerization tests and catalyst propertieswere carried out and determined in accordance with the general proceduredescribed above.

                                      TABLE II                                    __________________________________________________________________________                                   Catalyst Properties                                   Activation                        Composition                          Comparative                                                                          System.sup.(a)                                                                           Treatment    Cat. Eff.                                                                          C.sub.7 Insol.                                                                     Mol Ratio                                                                           Wt. %                          Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub.4                                                                          ° C.                                                                      Hrs  Yield %                                                                            W/W  %    Al:Ti Al,Ti,Cl.sup.(b)               __________________________________________________________________________    Ex. 1  0.6                                                                             1  1     65 2    100  141  98.4 0.09  92.8                           7      0.6                                                                             0  2     65 2    81   99   77   0.06  92                             8      0.9                                                                             0  5     35 1    93   90   98.5 0.02  85                                               65 2                                                        9      0.6                                                                             1  0     65 3    88   121  90.4 0.10  94                             10     0.6                                                                             1  0     80 3    70   123  97.2 0.05  100                            11     0.6                                                                             1  0     80 5    43   134  97.7 0.05  90                             __________________________________________________________________________     .sup.(a) Mol ratios of Bu.sub.2 C:C.sub.2 Cl.sub.6 :TiCl.sub.4 per 1 mol      TiCl.sub.3 in reduced solids.                                                 .sup.(b) Weight percent, as determined by xray fluorescence.             

The results in Table II show that catalyst treated with a dilutesolution of TiCl₄ (8.4 volume percent TiCl₄) has inferior polymerizationproperties to one treated sequentially with a concentrated TiCl₄solution (40 volume percent) (Comp. Ex. 7 vs. Comp. Ex. 8). In Comp. Ex.7, inadequate crystal conversion was achieved using the dilute TiCl₄solution as indicated by the low C₇ Insol. % (77%) and concomitant browncolor of the activated catalyst observed.

A comparison of Comp. Exs. 8, 9, 10 and 11 shows that it is necessary touse a high treatment temperature (80° C.) in order to obtain goodcrystal conversion of the catalyst when the activation system consistsof n-butyl ether and C₂ Cl₆. Specifically, in Comp. Ex. 9, mildtreatment (65° C., 3 hours) resulted in a brown-purple catalyst havingonly 90.4% C₇ Insol. properties. In Comp. Exs. 10 and 11 (80° C., 3 and5 hours, respectively), good crystal conversion was achieved, asindicated by the resulting purple color and C₇ Insol. % of 97.2 and97.7, respectively. However, at the high temperatures employed in thoseComparative Examples, the resulting catalyst yield was only 70 and 43%,respectively, based upon theoretical.

A comparison of Comp. Exs. 7 and 9, 10 and 11 to Example 1 clearlyverifies the synergism achieved by employing an activation system ofchlorinated hydrocarbon, low concentration of TiCl₄ in the presence ofthe ether complexing agent in accordance with the present invention. Atthe same treatment temperature employed (65° C.), the inventiveactivation system provided essentially complete crystal conversion withcatalyst properties clearly superior to treatment with activationsystems not containing either C₂ Cl₆ or TiCl₄ (Example 1 vs. Comp. Exs.7 and 9). The synergistic activation system also provides a catalystwith polymerization properties superior to that prepared in the absenceof TiCl₄ at a higher temperature (Example 1 vs. Comp. Exs. 10 and 11).Yet, as this latter comparison shows, the synergistic activation systemresults in the attainment of a 100% catalyst yield, vs. only 70% and 43%yields attained in Comp. Exs. 10 and 11.

EXAMPLES 2-5

Several samples (5.0 g) of brown, beta-crystalline reduced solidprepared according to the general procedure described above (TiCl₄ :DEACmol ratio=1) were added to 250 ml glass bottles containing a magnet anda solution of C₂ Cl₆ in n-heptane. To the respective slurries were addedspecific amounts of TiCl₄ and n-butyl ether and the mixtures were heatedfor the specified times after which the resulting treated solids werefiltered, washed 5 times with boiling heptane (50 cc fractions), driedunder reduced pressure, weighed and evaluated in the polymerizationsystem described above. The mol ratios of the activation systemreagents, activation conditions and catalyst properties and performanceare tabulated in Table III.

                                      TABLE III                                   __________________________________________________________________________                             Catalyst Properties                                         Activation                     Composition                                    System.sup.(a)                                                                         Treatment   Cat. Eff.,                                                                         C.sub.7 Insol.                                                                     Mol Ratio                                                                          Wt. %                              Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub.4                                                                        ° C.                                                                      Hrs                                                                              Yield %.sup.(c)                                                                     W/W  %    Al:Ti                                                                              Al,Ti,Cl.sup.(b)                   __________________________________________________________________________    2      0.6                                                                             1  0.2 65 3  107   103  94.5 0.10 102                                3      0.6                                                                             1  0.5 65 3  110    75  96.3 0.10 101                                4      0.8                                                                             1  1   65 2  109   105  95.3 0.10 92.1                               5      0.6                                                                             1  2   65 2  115   113  98.2 0.07 100                                __________________________________________________________________________     .sup.(a) Mol ratios of Bu.sub.2 O:C.sub.2 Cl.sub.6 :TiCl.sub.4 per 1 mol      TiCl.sub.3 in reduced solids.                                                 .sup.(b) Weight percent, as determined by xray fluorescence.                  .sup.(c) In cases where yields exceed 100% of theoretical, the added          TiCl.sub.4 reacts with the EtAlCl.sub.2 in the catalyst to form additiona     deltaTiCl.sub.3 in situ.                                                 

The data of Table III show the synergism of the activation system of thepresent invention is achieved at varying concentrations of TiCl₄ rangingfrom 2 volume percent (Example 2) to 4 volume percent (Example 3). Ineach Example 2-5, the catalyst was recovered in yields of at least 100%theoretical and polymerization properties of efficiency andstereospecificity were excellent. Additionally, it is noted thatcatalyst yields of the Examples were in excess of 100% theoretical,apparently due to added TiCl₄ reacting with ethylaluminum dichloride inthe treated catalyst to form additional delta-type TiCl₃ in situ. Hence,the present invention provides an additional advantage over techniqueswhich employ only a chlorinated hydrocarbon and/or ether in anactivation step.

EXAMPLES 6-15

Several samples (1.0 g) of brown, beta-crystalline reduced solidsprepared according to the general procedure described above wererespectively added to 250 ml glass bottles, each containing a magnet. Tothe flasks were added specified amounts of C₂ Cl₆ solution, TiCl₄ and aLewis base complexing agent. The respective slurries were heated at 80°C. for specified lengths of time. Following activations, the catalystswere allowed to settle, filtered, washed, dried and weighed as describedhereinabove. Each catalyst sample was then crushed and examined under amicroscope to determine their color. The activation conditions andresults are tabulated in Table IV.

                                      TABLE IV                                    __________________________________________________________________________           Activation                                                                    System.sup.(a)     Treatment                                           Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub.4                                                                         E        ° C.                                                                      Hrs                                                                              Yield %                                                                            Catalyst Color                           __________________________________________________________________________    6      0.6                                                                             1  1   p-methylanisole                                                                         80 5   72  Purple                                   7      0.7                                                                             1  1   diisopentyl ether                                                                       80 3  100  Purple                                   8      0.7                                                                             1  1   di-n-pentyl ether                                                                       80 3  100  Purple                                   9      1 1  1   di-n-hexyl ether                                                                        80 3  100  Purple                                   10     2 1  1   "         80 3  100  Purple                                   11     0.5                                                                             2  1   "         80 5   95  Purple                                   12     0.5                                                                             1  2   "         80 1  100  Purple                                   13     0.7                                                                             1  1   anisole   80 3  100  Purple                                   14     0.7                                                                             1  1   propyl phenyl ether                                                                     80 3  100  Purple                                   15     0.6                                                                             1  1   n-butyl ether                                                                           80 3   95  Purple                                   __________________________________________________________________________     .sup.(a) Mol ratios of Lewis base:chlorinated hydrocarbon and TiCl.sub.4      per 1 mol TiCl.sub.3 in reduced solids.                                  

The results of Table IV show the flexibility of the present invention inthe type and amount of Lewis base (ether) used in the activation system.In each Example, crystal conversion of the catalyst was obtained, asdemonstrated by the resulting purple color. Additionally, the data ofTable IV shows that even at high activation temperature (80° C.), theyield of activated catalyst is the same when TiCl₄ is present in theactivation system. Compare the results of Table IV, particularly Example15, to Comparative Examples 10 and 11, Table II. Hence, the synergisticactivation system of the invention provides wide latitude in activationconditions of temperature and time to obtain crystal conversion with noloss in catalyst yield.

EXAMPLES 16-23

Several samples (1.0 g) of brown, beta-crystalline reduced solidsprepared according to the general procedure described above were addedto 250 ml glass bottles, each containing a magnet. To the bottles wereadded specified amounts of chlorohydrocarbon solutions in n-heptane,TiCl₄ and n-butyl ether. The slurries were heated at 65° C. for 3 hours.Following the activation treatment, the catalyst solids were allowed tosettle, filtered, washed, dried and weighed as described hereinbefore.The treated catalyst samples were crushed and examined under amicroscope to determine their color. Details of the Examples and resultsare tabulated in Table V.

                                      TABLE V                                     __________________________________________________________________________           Activation System.sup.(d)                                                                       Treatment                                            Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub. 4                                                                         RX     ° C.                                                                      Hrs                                                                              Yield %                                                                             Catalyst Color                           __________________________________________________________________________    16     0.6                                                                             1  0    CCl.sub.4                                                                             65 3  <50   Brown                                    17     0.6                                                                             1  1    CCl.sub.4                                                                             65 3   71   Purple.sup.(b)                           18     0.6                                                                             1  0    CHCl.sub.3                                                                            65 3  <30   Brown                                    19     0.6                                                                             1  1    CHCl.sub.3                                                                            65 3  >70   Purple                                   20     0.6                                                                             1  0    CH.sub.2 Cl.sub.2                                                                     65 3  <30   Brown                                    21     0.6                                                                             1  1    CH.sub.2 Cl.sub.2                                                                     65 3  >70   Purple                                   22     0.6                                                                             1  0    CH.sub.2 Cl CCl.sub.3                                                                 65 3  <30   Brown                                    23     0.6                                                                             1  1    CH.sub.2 Cl CCl.sub.3                                                                 65 3  >70   Purple                                   __________________________________________________________________________     .sup.(a) Mol ratios nbutyl ether:chlorinated hydrocarbon:TiCl.sub.4 per 1     mol TiCl.sub.3 in reduced solids.                                             .sup.(b) Catalyst properties:                                                 Catalyst Efficiency, W/W: 82                                                  C.sub.7 Insolubles, %: 97.6                                              

The results of Table V, the unexpected synergism of TiCl₄ with variouschlorohydrocarbons having stable chloride-carbon bonds in activating thereduced solids and concomitantly increasing of the yield of treatedcatalyst. At the treatment conditions employed, none of the catalystswere activated by crystal conversion without the TiCl₄ in the activationsystem (Examples 16, 18, 20, and 22). Additionally, catalyst yield ofthese Examples were extremely low. However, in those Examples where theTiCl₄ was present (17, 29, 21,23), catalyst yields were increased andcrystal conversions obtained. It will be noted that each of thechlorinated hydrocarbons of Table V have more stable chloridecarbonbonds than hexachloroethane.

COMPARATIVE EXAMPLES 12-13

Two samples (5.0 g) of brown, beta-crystalline reduced solids preparedaccording to the general procedure described above, were respectivelytreated with specified combinations of n-butyl ether andtetrachloroethylene (a chlorinated hydrocarbon with vinyllic chloridebond) as described above. The recovered catalysts were then tested inthe above-described polymerization system. The activation conditions andresults are tabulated in Table VI.

                                      TABLE VI                                    __________________________________________________________________________                            Catalyst Properties                                          Activation                 Composition                                 Comparative                                                                          System.sup.(a)                                                                         Treatment  Cat. Eff.,                                                                          C.sub.7 Insol.                                                                     Mol Ratio                                                                           Wt. %                             Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub.4                                                                        ° C.                                                                      Hrs                                                                              Yield %                                                                            W/W   %    Al:Ti Al,Ti,Cl.sup.(b)                  __________________________________________________________________________    12     0.8                                                                             1.0                                                                              0   80 4  --    75   64   0.11  93                                13     0.8                                                                             1.2                                                                              0   80 5  --   131   71   0.07  93                                __________________________________________________________________________     .sup.(a) Mol ratios of Bu.sub.2 O:C.sub.2 Cl.sub.4 :TiCl.sub.4 per 1 mol      TiCl.sub.3 in reduced solids.                                                 .sup.(b) Weight percent, as determined by xray fluorescence.             

The results of Table VI show that the activation system of n-butyl etherand tetrachloroethylene and treatment conditions employed did not resultin crystal conversion of the reduced solids.

EXAMPLES 24-30

Several samples (5.0 g) of brown, beta-crystalline reduced solidsprepared according to the general procedure described above were treatedwith varying amounts of tetrachloroethylene, TiCl₄ and n-butyl ether(added in that order) under varying conditions, all as specified inTable III. The resulting catalysts, recovered as previously describedherein, were then tested in the abovedescribed polymerization system.Details of the Examples are set forth in the following Table VII.

                                      TABLE VII                                   __________________________________________________________________________                               Catalyst Properties                                       Activation                 Composition                                        System.sup.(a)                                                                         Treatment  Cat. Eff.,                                                                          C.sub.7 Insol.                                                                     Mol Ratio                                                                           Wt. %                             Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub.4                                                                        ° C.                                                                      Hrs                                                                              Yield %                                                                            W/W   %    Al:Ti Al,Ti,Cl.sup.(b)                  __________________________________________________________________________    24     0.6                                                                             0.5                                                                              1   85 3  135  78    96.1 0.09  100                               25     0.6                                                                             1  2   65 5  134  60    94.9 0.08  100                               26     0.6                                                                             1  2   65 3  134  71    95.2 0.08  101                               27     1 1  2   65 3  133  90    97.3 0.10  105                               28     0.6                                                                             1  2   65 1  125  62    92.5 0.11  100                               29     0.6                                                                             1  2   65 2   97  128   98.0 0.04   92                               30     0.1                                                                             1  2   65 2  148  35    89.0 0.81  101                               __________________________________________________________________________     .sup.(a) Mol ratios of Bu.sub.2 O:C.sub.2 Cl.sub.4 :TiCl.sub.4 per 1 mol      TiCl.sub.3                                                                    .sup.(b) Weight percent, as determined by xray fluorescence.             

A comparison of the results of Table VII (Examples 24-29) to those ofTable VI (Comparative Examples 12-13) shows that the addition of a smallamount of TiCl₄ to the n-butyl ether/C₂ Cl₄ activation system results incrystal conversion of the reduced solids, even at milder treatmentconditions of 65° C. Compare C₇ Insol. % of said Examples. Example 30shows the necessity of utilizing more than about 0.1 mol n-butyl ether:1mol TiCl₃ in the reduced solids in order to obtain catalyst crystalconversion.

EXAMPLES 31-37

Seven samples (5.0 g) of brown, beta-crystalline reduced solids preparedaccording to the general procedure described above were treated withspecified amounts of titanium tetrachloride, n-butyl ether and specifiedchlorinated hydrocarbons having a vinyllic chlorine-bond under varyingconditions, all as specified in Table III. The resulting catalysts wererecovered, tested in the polymerization system and observed for color,all as previously described. Details of the Examples are set forth inthe following Table VIII.

                                      TABLE VIII                                  __________________________________________________________________________           Activation                  Catalyst Properties                               System.sup.(a)   Treatment  Cat. Eff.,                                                                         C.sub.7 Insol.                        Example No.                                                                          E:                                                                              RX:                                                                              TiCl.sub.4                                                                         RX     ° C.                                                                      Hrs                                                                              Yield %                                                                            W/W  %    color                            __________________________________________________________________________    31     0 2  0   chlorobenzene                                                                         110                                                                              2  100  51   90   Brown                            32     0 2  0   p-chloroanisole                                                                       90 2  101  67   70   Brown                            33     0 2  0   p-chloroanisole                                                                       110                                                                              2  100  7    80   Brown                            34     0.7                                                                             1  0   benzyl chloride                                                                       80 5  100  34   94   Brown                            35     1.0                                                                             2  0   chlorobenzene                                                                         110                                                                              2   91  57   80   Brown                            36     0.7                                                                             1.2                                                                              0   chlorobenzene                                                                         90 2   92  61   75.0 Brown                            37     0.7                                                                             1.2                                                                              1   chlorobenzene                                                                         90 2  100  81   96.8 Purple                           __________________________________________________________________________     .sup.(a) Mol ratios nbutyl etherchlorinated hydrocarbon:TiCl.sub.4 per 1      mol TiCl.sub.3 in reduced solids.                                        

The results of Table VIII show that, even at high activation conditions,the employment of chlorobenzene, p-chloroanisole or benzyl chloride,either alone or with n-butyl ether in the activation system did notresult in crystal conversion of the reduced solids. However, as shown byExample 37, the addition of only a minor amount of titaniumtetrachloride to the chlorobenzene and n-butyl ether resulted in suchcrystal conversion (verified by catalyst properties) at the sameactivation conditions of Example 36.

What is claimed is:
 1. In a process for the stereopolymerization ofalpha-olefins wherein an alpha-olefin is contacted with a cocatalystsystem comprising a titanium trichloride containing compound catalystand an aluminum alkyl, as cocatalyst, under polymerization conditions,the improvement comprising:employing as said titanium trichloridecompound catalyst component a titanium trichloride catalyst complexproduced by a process comprising:(a) contacting titanium tetrachloridewith an organo metal compound of the formula R_(n) AlX_(3-n), wherein Ris a group having 1 to 18 carbon atoms selected from alkyl or aryl, X isa halogen and n is a numeral within the range of 1≦n≦3 at about -50° toabout 100° C. in an inert diluent to obtain a reduced solids product;(b) cntacting the reduced solids of (a) simultaneously with achlorinated hydrocarbon and titanium tetrachloride in the presence of aLewis base complexing agent, said chlorinated hydrocarbon, titaniumtetrachloride and Lewis base complexing agent being present in amountsof about 0.1 to about 10 mols chlorinated hydrocarbon, about 0.1 toabout 2.0 mols titanium tetrachloride and about 0.1 to about 2.0 molsLewis base complexing agent per one mole of titanium trichloride in thereduced solids of (a), and said titanium tetrachloride being in aconcentration of about 2 to about 15 volume percent at an elevatedtemperature within the range of from about 50° C. to about 150° C. forabout 5 minutes to about 10 hours until a crystal conversion of thereduced solids product of (a) is obtained; and (c) recovering theresulting activated reduced solids product as said titanium trichloridecatalyst complex in high yield.
 2. The process of claim 1 wherein thealpha-olefin comprises at least propylene.
 3. The process of claim 1wherein said step (b) is carried out under conditions of elevatedtemperature, for a time and at a titanium tetrachloride concentrationsuch that the recovered titanium trichloride catalyst complex of (c) hasalpha-olefin polymerization properties superior to titanium trichloridecatalyst complexes obtained by treating the reduced solids of (a) underthe same conditions of elevated temperature and time in the absence ofsaid titanium tetrachloride or said chlorinated hydrocarbon.
 4. Theprocess of claim 1 wherein said step (b) is carried out under conditionsof elevated temperature, for a time and at a titanium tetrachlorideconcentration such that the activated reduced solids recovered in step(c) is greater than the amount of titanium trichloride catalystcomplexes obtained by treating the reduced solids of (a) under the sameconditions of elevated temperature and time in the absence of saidtitanium tetrachloride.
 5. The process of claim 1 wherein thechlorinated hydrocarbon is selected from chlorinated saturatedhydrocarbons, chlorinated unsaturated hydrocarbons or mixtures thereof,said chlorinated hydrocarbons having from 1 to 8 carbon atoms permolecule.
 6. The process of claim 5 wherein the chlorinated hydrocarbonis hexachloroethane, the Lewis base complexing agent is n-butyl etherand the mol ratio of n-butyl ether to hexachloroethane to titaniumtetrachloride is about 0.6:1:1.
 7. The process of claim 5 wherein saidchlorinated hydrocarbon is tetrachloroethylene, the ether is n-butylether and the mol ratio of n-butyl ether to tetrachloroethylene totitanium tetrachloride is about 0.6:1:2.